[patch 02/71] poll/select: initialize triggered field of struct poll_wqueues

From: Greg KH
Date: Fri Sep 04 2009 - 20:20:41 EST

2.6.30-stable review patch. If anyone has any objections, please let us know.

From: Guillaume Knispel <gknispel@xxxxxxxxxxxxxxxxx>

commit b2add73dbf93fd50f00564d7abc3e2b9aa9dd20c upstream.

The triggered field of struct poll_wqueues introduced in commit
5f820f648c92a5ecc771a96b3c29aa6e90013bba ("poll: allow f_op->poll to

It was first set to 1 in pollwake() (now __pollwake() ), tested and
later set to 0 in poll_schedule_timeout(), but not initialized before.

As a result when the process needs to sleep, triggered was likely to be
non-zero even if pollwake() is not called before the first
poll_schedule_timeout(), meaning schedule_hrtimeout_range() would not be
called and an extra loop calling all ->poll() would be done.

This patch initialize triggered to 0 in poll_initwait() so the ->poll()
are not called twice before the process goes to sleep when it needs to.

Signed-off-by: Guillaume Knispel <gknispel@xxxxxxxxxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

fs/select.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/select.c
+++ b/fs/select.c
@@ -110,6 +110,7 @@ void poll_initwait(struct poll_wqueues *
init_poll_funcptr(&pwq->pt, __pollwait);
pwq->polling_task = current;
+ pwq->triggered = 0;
pwq->error = 0;
pwq->table = NULL;
pwq->inline_index = 0;

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